ipv6: copy prefsrc setting when copying route entry

commit c3968a857a
('ipv6: RTA_PREFSRC support for ipv6 route source address selection')
added support for ipv6 prefsrc as an alternative to ipv6 addrlabels,
but it did not work because the prefsrc entry was not copied.

Cc: Daniel Walter <sahne@0x90.at>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -1756,6 +1756,7 @@ static struct rt6_info * ip6_rt_copy(struct rt6_info *ort)
 #ifdef CONFIG_IPV6_SUBTREES
 		memcpy(&rt->rt6i_src, &ort->rt6i_src, sizeof(struct rt6key));
 #endif
+		memcpy(&rt->rt6i_prefsrc, &ort->rt6i_prefsrc, sizeof(struct rt6key));
 		rt->rt6i_table = ort->rt6i_table;
 	}
 	return rt;